Semiconductor devices communicate with their environment of use by accepting electrical impulses supplied by an external source (such as a circuit board) and conducting these impulses to electrical circuits contained on a semiconductor chip. The semiconductor chip reacts to the input in a predetermined manner to generate output. The input and output of electrical impulses to the semiconductor device occur over multiple paths of electrically conducting material, generally referred to as leads.
The traditional structure of one of these devices consists of having a semiconductor die with an edge having a row of individual bonding pads regularly spaced and arrayed at the periphery of one edge of the semiconductor die. A pattern of individual leads is also present that are usually secured to an external IC package or structure. Individual bond wires normally connect a single lead to an individual bond pad. In a traditional embodiment the pattern of individual leads, each of the leads corresponds to one of the bonding pads and is substantially perpendicular to the edge of the die. In other approaches, bonding pads are included along one or more perimeter edges of the semiconductor die.
As semiconductor chips have decreased in size, one of the limiting factors has been the number of available I/O pathways for a given chip. As lead and lead frame technology has progressed, it has been desirable to maximize the number of individual leads that are available in a lead frame. To effectively increase the number of I/O pathways, both the lead count and the number of bonding pads are typically increased. This conflicts with the fact that the die size remains the same and that the leads cannot short with each other leads even when the number of bonding pads have been increased by creating an inner row of bonding pads. This approach leads to devices having higher pin count, which renders a more difficult to design and manufacturing process with little return for the investment.
With the evolution of the consumer market, silicon manufacturers have to provide many different devices belonging to the same family architecture to allow OEM or end customers to build attractive products with up-to-date features. With the market evolving quickly with dropping prices, it is not possible to offer all features on a single chip device because the pin count would become high and the device price too expensive. The common way to avoid a high pin count is to multiplex interfaces. Generally, the multiplexing control is accomplished by coding a configuration on dedicated device pins connected externally to Vdd (source) or Vss (ground).
By fabricating integrated circuits that can be configured into any of several different functional products, manufacturers seek to capitalize on a number of advantages. Multi-configurable integrated circuits permit greater flexibility in meeting customer design requirements. Such circuits also allow reduced tooling and fabrication costs--as some of the steps which would be duplicated during production of separate functional products can be eliminated by producing a single, multi-configurable integrated circuit. The multi-configurable integrated circuit also reduces the necessity to keep a large inventory of several functionally-different integrated circuit reticle sets on hand so as to meet the customer's needs.
When selecting a particular function or operating mode of a multi-function device, a variety of hook-up arrangements may be used, including: electrically connecting two or more bonding pads together, omitting specific connections, and transposing certain connections. Connecting two or more bonding pads typically involves connecting each pad individually to its respective lead by a connector wire, and then tying the two leads together with a jumper wire outside of the device package. Such an approach requires that two connector wires and two leads be provided for each pair of pads that are interconnected, and that the connector wires be routed over undesirable circuit areas. Consequently, the device is less reliable because of the additional connections, the excessive number of internal bond points and amount of connector wires; further, the device has a reduced number of functioning leads that may be brought out of the package.
Developing a cost-effective multi-configurable IC would be advantageous if the IC could increase the manufacturer's ability to use the same die for multiple uses without degrading the IC's functionality or integrity. In the IC market for wireless communication, for example, a first configuration of a multi-configurable IC device could be dedicated for a handset communicator application and a second configuration of the same multi-configurable IC device could be dedicated for a base communicator application. In another example, a multi-configurable IC device could be used for a handset device having a keypad scanning interface, and the same multi-configurable IC device could be sold with an altered configuration as a base communicator device having a telephone-answering machine function.
Accordingly, there is need for a cost-effective multi-configurable IC that overcomes the issues and problems discussed above.